1 / 67

TCP/IP Internetworking Protocols

Instructor: Wu-chang Feng. TCP/IP Internetworking Protocols. Current events. Willamette Week 9/22/2004. What’s going on?. I’ve been raided This course being offered as OGI CSE 524 PSU CS 510 (OG2) What does this mean for you and your degree? Questions about OGI/OHSU.

donalddiaz
Télécharger la présentation

TCP/IP Internetworking Protocols

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Instructor: Wu-chang Feng TCP/IP Internetworking Protocols

  2. Current events • Willamette Week 9/22/2004

  3. What’s going on? • I’ve been raided • This course being offered as • OGI CSE 524 • PSU CS 510 (OG2) • What does this mean for you and your degree? • Questions about OGI/OHSU. • Dick Fairley <fairleyd@ohsu.edu> • Questions about Portland State. • Cindy Brown <cbrown@cs.pdx.edu>

  4. Goals of course • Introductory course on Internet protocols • Higher-level design decisions and their impact • Encyclopedia of essential Internet protocols and algorithms • Those with a working knowledge of Internet protocols should skip this quarter and go directly to… • CS 610: Advanced Topics in Networking (Winter 2005) Singh & Feng

  5. Syllabus • http://www.cse.ogi.edu/class/cse524/ • Office hours • Wednesdays, 6:30pm-8:30pm FAB 115 • Look for my cubicle • TA and TA office hours: TBD • Required book • Kurose/Ross, “Computer Networking: A Top-Down Approach Featuring the Internet”, 2nd ed.

  6. Programming project • Implement a useful network protocol • Can use any available SDK • Protocol should be accompanied with a specification (a. la. RFCs) • Example protocols • Application: P2P, IRC, IM, On-line games, Overlay network, On-line photo album • Transport: Extending TCP, SCTP, UDP or writing your own • Network: Extending IP, ICMP, Routing • Deliverables • Soft and hard copies of code • Demo and code walkthrough with TA/instructor • Wednesday 12/8/2004 5:30-7:30pm • Thursday 12/9/2004 5:30-7:30pm

  7. Outline of course • Internet architecture, history, future (Chapter 1) • Application layer (Chapter 2) • Transport layer (Chapter 3) • Network layer (Chapter 4) • Physical, data-link layers (Chapter 5)

  8. About the course • Extremely condensed • Not comprehensive • Hundreds of protocols • PSU/OCATE CS 510 - Internet Routing • PSU/OCATE CS 510 - Network Management/Security • PSU/OCATE CS 510 Multimedia Networking • PSU/OCATE CS 510 Advanced Networking

  9. Overview, Internet architecture, Internet history CSE524: Lecture 1

  10. Internet Architecture • http://www.nap.edu/html/coming_of_age/ • http://www.ietf.org/rfc/rfc1958.txt • Why did the Internet win? • Packet switching over circuit switching • “Hourglass” design • End-to-end architecture • Layering of functionality • Distributed design, decentralized control • Superior organizational process • Al Gore 

  11. Packet-switching vs. Circuit Switching • mesh of interconnected routers • the fundamental question: how is data transferred through net? • circuit switching: dedicated circuit per call: telephone network • packet-switching: data sent thru net in discrete “chunks”

  12. Circuit Switching Resources reserved for “call” on an end to end basis • link bandwidth, switch capacity • dedicated resources: no sharing • circuit-like (guaranteed) performance • call setup and admission control required

  13. Circuit Switching network resources (e.g., bandwidth) divided into “pieces” • pieces allocated to calls • resource piece idle if not used by owning call (no sharing) • dividing link bandwidth into “pieces” • frequency division • time division

  14. Case study: Circuit Switching • 1890-current: Phone network • Fixed bit rate • Mostly voice • Not fault-tolerant • Components extremely reliable • Global application-level knowledge throughout network

  15. resource contention: • aggregate resource demand can exceed amount available • congestion: packets queue, wait for link use • store and forward: packets move one hop at a time • transmit over link • wait turn at next link Bandwidth division into “pieces” Dedicated allocation Resource reservation Packet Switching each end-end data stream divided into packets • user A, B packets share network resources • each packet uses full link bandwidth • resources used as needed,

  16. Case study: Packet Switching • 1981-current: Internet network • Variable bit rate • Mostly data • Fault-tolerant • Components not extremely reliable (versus phone components) • Distributed control and management

  17. Packet switching versus circuit switching • N users over 1Mbs link • Each user xmits 100kbps when “active”, active 10% of time • Circuit-switching => supports 10 users • Packet switching: • With 35 users, P(active_users>10) < 0.004 • Allows more users to use network • “Statistical multiplexing gain” N users 1 Mbps link

  18. D E Packet Switching 10 Mbs Ethernet C A statistical multiplexing 1.5 Mbs B queue of packets waiting for output link 45 Mbs

  19. Packet switching versus circuit switching Is packet switching a “slam dunk winner? • Great for bursty data • Resource sharing, no call setup • Bad for applications with hard resource requirements • Packet delay and loss due to congestion • Protocols needed for reliable data transfer and congestion control • Applications must be written to handle congestion • Q: How to provide circuit-like behavior? • Providing guarantees an unsolved problem • Common practice => overprovision Back

  20. Hourglass design

  21. Hourglass design • D. Clark, “The design philosophy of the DARPA Internet”, SIGCOMM 1988, August 16 - 18, 1988. http://www.acm.org/pubs/citations/proceedings/comm/52324/p106-clark/

  22. Hourglass design • Only one protocol at the Internet level • Minimal required elements at the narrowest point • IP – Internet Protocol • http://www.rfc-editor.org/rfc/rfc791.txt • http://www.rfc-editor.org/rfc/rfc1812.txt • Unreliable datagram service • Addressing and connectionless connectivity • Fragmentation and assembly • Innovation at the edge • Phone network: dumb edge devices, intelligent network • Internet: dumb network, intelligent edge devices

  23. Hourglass design • Simplicity allowed fast deployment of multi-vendor, multi-provider public network • Ease of implementation • Limited hardware requirements • Eventual economies of scale • Designed independently of hardware • Hardware addresses decoupled from IP addresses • IP header contains no data/physical link specific information • Allows IP to run over any fabric

  24. Hourglass design • Waist expands at transport layer • Two dominant services layered above IP • TCP – Transmission Control Protocol • Connection-oriented service • http://www.rfc-editor.org/rfc/rfc793.txt • UDP – User Datagram Protocol • Connectionless service • http://www.rfc-editor.org/rfc/rfc768.txt

  25. Hourglass design • TCP – Transmission Control Protocol • Reliable, in-order byte-stream data transfer • Acknowledgements and retransmissions • Flow control • Sender won’t overwhelm receiver • Congestion control • Senders won’t overwhelm network

  26. Hourglass design • UDP – User Datagram Protocol • Unreliable data transfer • No flow control • No congestion control

  27. Hourglass design • What uses TCP? • HTTP, FTP, Telnet, SMTP, NNTP, BGP, IMAP, POP • What uses (mainly) UDP? • SNMP, NTP, NFS, RTP (streaming media, IP telephony, teleconferencing), multicast applications • Many protocols can use both • Check out /etc/services on *nix or C:\WIN*\system32\services • IANA • http://www.iana.org/assignments/port-numbers

  28. Hourglass design • Question? • Are TCP, UDP, and IP enough? • What other functionality would applications need?

  29. Hourglass design • Security? • Quality-of-service? • Reliable, out-of-order delivery service? • Handling greedy sources? • Accounting and pricing support? • IPsec, DiffServ, SCTP, …. Back

  30. End-to-end principle • J. H. Saltzer, D. P. Reed and D. D. Clark “End-to-end arguments in system design”, Transactions on Computer Systems, Vol. 2, No. 4, 1984 • http://www.acm.org/pubs/citations/journals/tocs/1984-2-4/p277-saltzer/

  31. End-to-end principle • Where to put the functionality? • In the network? At the edges? • End-to-end functions best handled by end-to-end protocols • Network provides basic service: data transport • Intelligence and applications located in or close to devices at the edge • Violate principle as a performance enhancement

  32. End-to-end principle • The good • Basic network functionality allowed for extremely quick adoption and deployment using simple devices • The bad • New network features and functionality are impossible to deploy, requiring widespread adoption within the network • IP Multicast, QoS Back

  33. Application Host-to-host connectivity Link hardware Layering • Modular approach to network functionality • Technique to simplify complex systems • Example:

  34. Layering Characteristics • Each layer relies on services from layer below and exports services to layer above • Hides implementation - layers can change without disturbing other layers (black box) • Examples • Topology and physical configuration hidden by network-layer routing • Applications require no knowledge of this • New applications deployed without coordination with network operators or operating system vendors

  35. Layering in Protocols • Set of rules governing communication between network elements (applications, hosts, routers) • Protocols specify: • Interface to higher layers (API) • Interface to peer • Format and order of messages • Actions taken on receipt of a message • Interface defines interaction

  36. Layering in Networks: OSI Model • Physical: how to transmit bits • Data link: how to transmit frames • Network: how to route packets • Transport: how to send packets end2end • Session: how to tie flows together • Presentation: byte ordering, security • Application: everything else

  37. OSI Layers and Locations Application Presentation Session Transport Network Data Link Physical Switch Host Router Host

  38. Layer Encapsulation User A User B Get index.html Connection ID Source/Destination Link Address

  39. Layering • Is Layering always good? • Sometimes.. • Layer N may duplicate lower level functionality (e.g., error recovery) • Layers may need same info (timestamp, MTU) • Strict adherence to layering may hurt performance

  40. Layering • Need for exposing underlying layers for optimal application performance • D. Tennenhouse and D. Clark. Architectural Considerations for a New Generation of Protocols. SIGCOMM 1990. • Intel employees: Tennenhouse is a networking “rock star” and your head of research • Application Layer Framing (ALF) • Enable application to process data as soon as it can • Expose application processing unit (ADU) to protocols • Integrated Layer Processing (ILP) • Layering convenient for architecture but not for implementations • Combine data manipulation operations across layers Back

  41. Distributed design and control • Requirements from DARPA • Must survive a nuclear attack • Reliability • Intelligent aggregation of unreliable components • Alternate paths, adaptivity • Distributed management & control of networks • Exceptions: TLDs and TLD servers, IP address allocation (ICANN) Back

  42. Superior organizational process • IAB/IETF process allowed for quick specification, implementation, and deployment of new standards • Free and easy download of standards • Rough consensus and running code • 2 interoperable implementations • Bake-offs • http://www.ietf.org/ • ISO/OSI • Comparison to IETF left as an exercise Back

  43. Internet History • Those who ignore the past are doomed to repeat it http://www.worldcom.com/about_the_company/cerfs_up/ • Where did it come from? • Who built it? • Why does it work? • Most of the original designers (old-timers) still around and active… • internet-history-request@postel.org

  44. Packet switching • Kleinrock, MIT (July 1961) • Theoretical feasibility of communications using packets instead of circuits • L. Kleinrock, "Information Flow in Large Communication Nets", RLE Quarterly Progress Report, July 1961. • L. Kleinrock, Communication Nets: Stochastic Message Flow and Delay, Mcgraw-Hill (New York), 1964.

  45. Conceptual “Internet” • J.C.R. Licklider, W. Clark, MIT (August 1962) • “On-line Man Computer Communication” • “Galactic network” concept of globally interconnected set of computers • Licklider goes to DARPA as head of computer research program (Oct. 1962)

  46. ARPANET • Roberts, (1966) • Puts idea of galactic computer network and packet switching together • Goes to DARPA as program manager • Plans for building “ARPANET” based on system • L. Roberts, "Multiple Computer Networks and Intercomputer Communication", ACM Gatlinburg Conf., October 1967.

  47. ARPANET • Structure and specification (August 1968) • RFQ to build IMPs (Interface Message Processors) • Packet switches which route packets • BBN (Bolt, Beranek, and Newman) wins contract • Kahn at BBN updates ARPANET design • Run over any fabric (separation of hardware and network addresses) • Support for multiple independent networks • First node UCLA (Sept. 1969) • 4 node ARPANET (Dec. 1969) SRI, UCSB, Utah • Initial hostname/address database (flat file: hosts.txt)

  48. RFCs • 1969: Crocker establishes RFC series of notes • Official protocol documentation • Printed on paper and snail mailed at first • Then available via ftp and now http • Open and free access to RFCs mandated • Effective, positive feedback loop • Key to quick development process (“time-to-market”) • Has changed considerably as of late... • Jon Postel RFC editor and protocol number assignment

  49. NCP • Crocker • Connectivity implemented • Require a host-to-host protocol standard for two ends to talk to each other • NCP (Network Control Protocol) defined (Dec. 1970) • Precursor to TCP • Deployed from 1971-1972 • Allows applications to be developed on top of network

  50. E-mail • BBN’s Tomlinson (Mar. 1972) • Time-shared systems at the time allow users to leave messages for each other • Extended to remote systems • Writes first e-mail application to send and read • Infamous “@” used

More Related